CN115795940A - Method for simulating galloping inhibition value of ice-coated conductor based on heavy hammer - Google Patents
Method for simulating galloping inhibition value of ice-coated conductor based on heavy hammer Download PDFInfo
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Abstract
The invention discloses a method for simulating the waving inhibition value of an ice-coated conductor based on a heavy hammer, which provides a heavy hammer arrangement scheme according to actual line parameters; based on a wire icing torsion model, the suppression effect of different heavy hammer arrangement schemes on torsion angles is researched, and based on modal analysis in ANSYS, the suppression effect of heavy hammers on galloping is analyzed. To achieve the above result, the present invention comprises the steps of: s1: conducting wire icing torsion statics simulation; s2: determining weight structureAnd (3) parameters, assuming that the section of the ice coating line is in a typical crescent shape, uniformly coating ice in a full span, simplifying a lumped mass system by adopting a lumped parameter model, combining the device with the whole line, and finding out the length L of the hammer handle meeting any torsion angle through an optimization equation p And the mass M of the hammer head p The optimal combination parameter of (2). S3: the optimal quality calculated by the above optimization model is the total quality of the entire span, as described at S2.
Description
Technical Field
The invention relates to the technical field of power transmission lines, in particular to a numerical simulation method for inhibiting galloping of an iced conductor based on a heavy hammer.
Background
The waving is that the wire generates self-excited vibration with low frequency (0.1-3 Hz) and large amplitude, and the forming of the waving mainly depends on three factors, namely, icing, wind excitation, and the structure and parameters of the circuit. The hazards caused by galloping are various, and serious power grid accidents are caused by flashover and tripping of light persons, damage of hardware fittings and insulators of heavy persons, strand breakage and wire breakage of wires and even tower collapse.
The arrangement of the heavy hammer on the wire is an effective method for suppressing the wire waving, and there are two explanations theoretically. Firstly, hanging a heavy hammer to increase the overall mass of the line and increase the critical wind speed value of the galloping; secondly, the hanging heavy hammer causes the inherent frequency of the overall transverse vibration of the line to be reduced, torsional resonance is avoided, and the critical ice wind value is increased. In the actual ice coating of the line conductor, the ice coating firstly appears on the upper side of the wind receiving surface in most cases, and the included angle between the ice coating and the gravity is less than 45 degrees. Generally, ice coating stiffness refers to the effect on the ability of the wire system to resist deformation after the wire is coated with ice. The process of changing rigidity by icing is as follows: if the windward side is on the upper side of the wire, when the wire is twisted by an external force, the gravity center of the ice coating will move downwards, the external force is cancelled, the wire is difficult to return to the original shape, and the gravity center of the whole wire and the ice layer is difficult to return to the original position, which is generally called negative rigidity. Therefore, the rigidity of ice coating is often regarded as a negative value.
Icing can increase negative stiffness severely, reducing overall torsional stiffness, resulting in a rapid decrease in the torsional natural frequency of the wire with less decrease in the transverse natural frequency. When the natural frequency of torsional vibration and the natural frequency of transverse vibration are equal, it will be possible to excite torsional self-oscillation. If a heavy hammer is fixed under the wire, the additional rigidity is positive, the overall torsional rigidity is increased, the inherent frequency of the offset torsional vibration is reduced, and therefore the capability of resisting external ice wind effect load of the wire is improved, and the running safety margin of the wire is further improved
And then, according to the mechanism of the weight for inhibiting the galloping, a method for inhibiting the twisting of the wire is provided, and the effect of the weight inhibition method on inhibiting the twisting of the ice coated on the wire is researched through the model, so that the icing hazard of the line is reduced. Therefore, the method for researching wire icing, providing an anti-icing and deicing method and effectively reducing the ice and snow disasters of the power transmission line has important significance and engineering application value.
Disclosure of Invention
The invention provides a method for simulating the waving inhibition value of an ice-coated conductor of a heavy hammer, which provides a heavy hammer arrangement scheme according to actual line parameters; based on a wire icing torsion model, the suppression effect of different heavy hammer arrangement schemes on torsion angles is researched, and based on modal analysis in ANSYS, the suppression effect of heavy hammers on galloping is analyzed. In order to achieve the above results, the invention adopts the following specific technical scheme:
s1: conducting static simulation of icing and twisting of the lead, wherein the static simulation of the lead mainly comprises the following steps:
1. defining related physical parameters of the line, including span, height difference, sag, wire diameter and the like;
2. defining the properties of the wire material, including elastic modulus, wire density and Poisson ratio;
3. the cell property is defined as a Beam188 cell, and the Beam188 cell is a three-dimensional Beam cell and has two nodes, each node of the cell has 6 degrees of freedom and can simulate tension, compression and torsion. Thus, the power conductor simulates an iced conductor with a Beam188 cell.
4. Establishing key points, creating a geometric model of the lead, executing grid division, releasing the freedom degrees of torsion and displacement in the lead, applying initial strain and the like.
5. After the steps of conducting the wire, opening the large deformation switch, applying gravity, and conducting wire shape finding under the condition that the axial force of the middle unit is used for iteration termination. And finally, calculating the twisting angle of the lead by applying the torque of the lead through the ice weight and the gravity center obtained by fluid simulation calculation.
S2: determining structural parameters of a heavy hammer, assuming that the section of an icing line is in a typical crescent shape, evenly icing in a full span, simplifying a lumped mass system by adopting a lumped parameter model, combining the device with the whole line, and finding out the length L of a hammer handle meeting any torsion angle through an optimization equation p And the mass M of the hammer head p The optimal combination parameter of (2).
S3: the optimal quality calculated by the above optimization model is the total quality of the entire span, as described at S2. According to the multipoint weighting principle, in one span, if a heavy object is arranged at different points in the span, a plurality of nodes can be formed, so that the wire system vibrates in a higher order, the vibration amplitude is reduced, and the damage to the transmission wire is reduced, therefore, the arrangement mode of the heavy hammer needs to be reasonably selected, and according to the heavy hammer node division principle, when a wire at a certain span waves, the waving can be transmitted from one span to the adjacent span. Likewise, within the same span, vibrations within a sub-span also induce vibrations of an adjacent sub-span. The frequency of the vibration waves transmitted from the adjacent gear, if being close to or even the same as the natural frequency of the gear, can cause resonance to excite strong sub-span oscillation, which is a problem to be considered in the anti-galloping design. Therefore, in order to prevent the occurrence of such resonance, it is necessary to make the natural frequencies of the adjacent subspans different from each other. If the heavy hammer is completely concentrated in the middle of the span, namely arranged at the 1/2 span, on one hand, the mass is concentrated at the 1 point, and the mechanical and electrical strength of the lead cannot be guaranteed; on the other hand, even if the midpoint does become a node and does not move any more, it is only the original pitch that is divided into two half pitches that can still dance. Meanwhile, when the height difference of the suspension points at the 2 ends is not large or is far smaller than the span, the natural frequencies of the two half pitches are similar due to good symmetry. Thus, once the waving occurs, the two will be coupled to each other through the nodes, forming a strong whole-gear waving. Therefore, even number of steps should be avoided in designing the weight layout. Based on the analysis, in order to research the effects of inhibiting the twisting and waving of the ice coated on the wire of the heavy hammer, the following 4 schemes are given for simulation: in the scheme 1, 4 heavy hammers are arranged at equal intervals and equal mass; in the scheme 2, 6 heavy hammers are arranged at equal intervals and equal mass; in the scheme 3, 8 heavy hammers are arranged at equal intervals and equal mass; scheme 4, 10 weights are equally spaced and equally mass arranged.
S4: based on the dynamic icing simulation in S1, a heavy hammer model is added. The effect of the weight on the wire twisting is derived from the torque and weight provided by the weight. Therefore, for the wire icing torsion simulation of the suspended weight, only the gravity provided by the weight needs to be added when the wire icing torsion simulation is performed in the step 5 in the step S1, the ice load torque and the weight torque are calculated together when the torsion angle is calculated, and in the statics simulation, the core parameters of the weight are the length of the hammer handle and the weight of the hammer head, and meanwhile, the weight can be twisted together with the wire, so that the hammer handle is simulated by adopting the large-rigidity BEAM unit BEAM188 with a given length, and the MASS21 unit with MASS effect only in the plumb direction is fixed at one end of the large-rigidity BEAM unit to simulate the hammer head. The rest simulation flows and the wire icing torsion simulation in the S1 are kept unchanged. The mode is the inherent vibration characteristic of the line conductor, and the relative natural vibration frequency can be intercepted by using the mode analysis in ANSYS software to research the waving suppression effect of the heavy hammer.
S5: determining the influence of a heavy hammer on a torsion angle, setting line conductor parameters, and calculating the mass 1070.5kg/km, the elastic modulus 77GPa, the conductor diameter 22.4mm, the span 230m, the height difference 0m and the horizontal tension 31kN; and (6) carrying out simulation. And comparing and analyzing the change of the torsion angle of the wire covered with ice for 10 hours under the four schemes, and drawing a relation curve of the torsion angle and the position in the gear.
S6: analyzing the inhibition effect of the heavy hammer on the waving, and based on a Nigol torsion mechanism: for a flexible cable structure such as a single conductor, the separation of the 3 < rd > order transverse vibration frequency and the 1 < st > order torsional vibration frequency may reflect its own galloping suppression capability. And introducing a resonance margin ζ quantitatively describes the degree of separation between the two frequencies.
The invention has the beneficial effects that:
the invention discloses a method for simulating the waving inhibition value of an ice-coated conductor of a heavy hammer, which provides a heavy hammer arrangement scheme according to actual line parameters; based on a wire icing torsion model, the suppression effect of different heavy hammer arrangement schemes on torsion angles is researched, and based on modal analysis in ANSYS, the suppression effect of heavy hammers on galloping is analyzed;
the weight can provide a strong anti-twisting moment effect for the ice-coated conductor to inhibit the twisting of the conductor in the ice-coating process, so that the ice-coating process of the conductor can continuously occur on one side (windward side). And along with the increase of the thickness of the ice coating, the phenomenon that the ice coating bonding moment can not resist the self gravity moment of the ice coating can occur, the macroscopic expression is that the ice coating falls off layer by layer, and particularly under the action of natural wind, the falling off can be particularly violent, so that the ice coating degree of the wire is reduced, the increase of the sag stress of the wire is reduced, and the safety and the stability of the operation of the wire are further improved.
Drawings
FIG. 1 is a set of optimization curves for weight parameters at different initial ice-setting angles;
FIG. 2 is a torsion angle distribution curve of different weight placement schemes;
FIG. 3 is a table of line parameters;
FIG. 4 shows frequency separation under operating conditions.
Description of reference numerals:
the degrees represented by the curves in FIG. 1 are 5 degrees, 10 degrees, 15 degrees, … … from top to bottom in sequence
The schemes represented by the curves in fig. 2 are "without weight", "scheme four (scheme 4)", "scheme three (scheme 3)", "scheme two (scheme 2)", and "scheme one (scheme 1)" in this order from top to bottom.
Detailed Description
The following description of the embodiments of the present invention refers to the accompanying drawings and examples:
the present invention is described in further detail below with reference to the drawings (tables) of the specification.
S1: conducting static simulation of icing and twisting of the lead, wherein the static simulation of the lead mainly comprises the following steps:
1. defining related physical parameters of the line, including span, height difference, sag, wire diameter and the like;
2. defining the properties of the wire material, including elastic modulus, wire density and Poisson ratio;
3. the cell property is defined as a Beam188 cell, and the Beam188 cell is a three-dimensional Beam cell and has two nodes, each node of the cell has 6 degrees of freedom and can simulate tension, compression and torsion. Thus, the power conductor simulates an iced conductor with a Beam188 cell.
4. Establishing key points, creating a geometric model of the lead, executing grid division, releasing the freedom degrees of torsion and displacement in the lead, applying initial strain and the like.
5. After the steps of conducting the wire, opening the large deformation switch, applying gravity, and conducting wire shape finding under the condition that the axial force of the middle unit is used for iteration termination. And finally, calculating the twisting angle of the lead by applying the torque of the lead through the ice weight and the gravity center obtained by fluid simulation calculation.
S2: determining structural parameters of a heavy hammer, assuming that the section of an ice coating line is in a typical crescent shape, uniformly coating ice in a full span, simplifying a lumped mass system by adopting a lumped parameter model, combining the device with the whole line, and determining the ice coating mass m of the lead with unit length i Comprises the following steps:
in the formula: r is the radius of the wire; delta is the ice thickness; ρ is the ice density.
The equivalent torque produced by crescent shaped eccentric icing is then:
in the formula: l is a span; theta 0 An initial ice-condensation angle (an included angle between a connecting line of the center of gravity of ice and the center of the section of the lead and a plumb line before the lead is not twisted and deformed); theta.theta. t The wire torsion angle caused by icing eccentric moment; e.g. of the type 0 The distance between the center of the wire and the center of gravity of the crescent ice coating can be from the bottomThe formula is obtained:
thus: the negative stiffness resulting from ice coating can be expressed as:
the positive stiffness generated by the weight can be calculated as follows:
in the formula: m p The mass of the hammer head of the heavy hammer; l is p Is the length of the hammer handle.
The equivalent moment of inertia of the ice coating and the weight is:
calculated according to a centralized parameter system, the natural frequency of torsional vibration of the system is as follows:
in the formula: f. of t The natural frequency of the torsional vibration of the order 1 of the system; k is a radical of e Calculating the equivalent torsional rigidity of the whole gear lead by a formula (9); j is a unit of e Is the equivalent moment of inertia of the wire.
In the formula: h 0 Is the tension of the wire; other parameters have the same meaning as above.
In the formula: m is the mass per unit length of the wire; the other parameters have the same meaning as above.
Substituting the above parameters into equation (8) to obtain:
transverse vibration natural frequency of the system:
in the formula: f. of v1 The system is the 1 st order transverse natural vibration frequency; the other parameters have the same meaning as above.
Based on the S1 analysis, the weight design criteria can be described as follows:
f t ＝Nf vn (13)
in the formula: n is a safety coefficient, and the larger N is, the larger frequency separation is; the value of N is 1.5 in reference; n is the order of the lateral vibration frequency to be protected, and Nigol recommends the third order natural frequency, namely: f. of t ＝Nf v3 But whether f is v4 、f v5 The above does not produce higher order coupling, and there is no sufficient theoretical basis at present. At least it can be concluded that: higher order couplings are less severe and dangerous than lower order couplings.
In simplified calculations, it is generally advisable to take v3 ＝3f v1 . In summary, equation (13) can be written as:
f t ＝1.5f v3 ＝4.5f v1 (14)
substituting equation (11) and equation (12) into equation (14) has:
initial ice angle θ 0 (since the torsion angle after hanging the weight is generally within 5 degrees, generally neglecting theta t ) Length L of hammer handle p And weight M of hammer head p All are unknown parameters, and it is difficult to directly solve the parameters. The purpose of the weight parameter optimization is to find out the weight parameter L which can satisfy any initial ice condensation angle p And M p The optimal combination of (a) is as follows: l is p And M p Are as small as possible. And meanwhile, the analysis is carried out from the view of safe and stable operation of the line: l is p The smaller the distance between the lead and the ground is, the larger the electrical safety of the lead is; m p The smaller the increase in the percent sag stress of the wire, the higher the mechanical and electrical safety of the wire. In summary, the weight parameter L can be obtained by combining with the related theory of optimization analysis in mathematics p And M p The determination problem of (a) is summarized as the following optimization model:
in the formula: m p (x)、L p (x) Are all optimization functions; x is an optimization design variable, namely: initial freezing angle theta 0 Length L of hammer handle p And weight M of hammer head p ；s i (x) For the constraint condition, find out the weight parameter (L) satisfying any torsion angle through the formula (16) p ,M p ) The optimization model is calculated from equation (16) according to fig. 3. Due to the initial ice-setting angle theta in practical engineering 0 Distribution range and installation limit, the parameter theta 0 And L p The distribution range of (c) is limited as follows: theta 0 ～[5°,45°]，L p ～[200mm,1000mm]. Taking an initial ice condensation angle every 5 degrees and taking a hammer handle length L at 10mm p The optimization curve of the weight parameter can be obtained, as shown in FIG. 1.
As can be seen from fig. 1: under the constraint of equation (15), the weight M of the hammer head p Length L of hammer handle p The change trends of (A) show the characteristic of decreasing first and then increasing, and the extreme points (the lowest points) are distributed on L p =600mm, andat the extreme point distribution, the minimum hammer weight M is increased along with the increase of the initial ice condensation angle p Gradually decreases. Since each point in the curve cluster is an optimized combination satisfying the formula (16), we aim to find the weight parameter (L) satisfying any torsion angle p ,M p ) From which we can determine: maximum of all curve nadirs, identified in the figure: l is p ＝600mm，M p =71.28kg, optimal combination.
S3: the optimal quality calculated by the above optimization model is the total quality of the entire span, as described at S2. According to the multipoint weighting principle, in one span, if heavy objects are arranged at different points in the span, a plurality of nodes can be formed, so that a line system vibrates in a higher order, the vibration amplitude is reduced, and the damage to a transmission line is reduced. Likewise, within the same span, vibrations within a sub-span also induce vibrations of an adjacent sub-span. The frequency of the vibration waves transmitted from the adjacent gear, if being close to or even the same as the natural frequency of the gear, can cause resonance to excite strong sublevel oscillation, which is a problem to be considered in the anti-galloping design. Therefore, in order to prevent the occurrence of such resonance, it is necessary to make the natural frequencies of the adjacent subspans different from each other. If the heavy hammer is completely concentrated in the middle of the span, namely arranged at the 1/2 span, on one hand, the mass is concentrated at the 1 point, and the mechanical and electrical strength of the lead cannot be guaranteed; on the other hand, even if the midpoint does become a node and does not move any more, it is only the original pitch that is divided into two half pitches that can still dance. Meanwhile, when the height difference of the suspension points at the 2 ends is not large or is far smaller than the span, the natural frequencies of the two half pitches are similar due to good symmetry. Thus, once the waving occurs, the two will be coupled to each other through the nodes, forming a strong whole-gear waving. Therefore, even number of steps should be avoided in designing the weight layout. Based on the analysis, in order to research the effects of inhibiting the twisting and waving of the ice coated on the wire of the heavy hammer, the following 4 schemes are given for simulation: in the scheme 1, 4 heavy hammers are arranged at equal intervals and equal mass; in the scheme 2, 6 heavy hammers are arranged at equal intervals and equal mass; in the scheme 3, 8 heavy hammers are arranged at equal intervals and equal mass; scheme 4, 10 weights are equally spaced and equally mass arranged.
S4: based on the dynamic icing simulation in S1, a heavy hammer model is added. The effect of the weight on the wire twisting is derived from the torque and weight provided by the weight. Therefore, for the wire icing torsion simulation of the suspended weight, only the gravity provided by the weight needs to be added when the wire is shaped in the step 5 of S1, and the ice load torque and the weight torque are calculated together when the torsion angle is calculated, in the statics simulation, the core parameters of the weight are the length of the hammer handle and the weight of the hammer head, and meanwhile, the weight can be twisted together with the wire, so that the large-rigidity BEAM unit BEAM188 with a given length is adopted to simulate the hammer handle, and the MASS21 unit with MASS effect only in the direction of the hammer head is fixed at one end of the weight to simulate the hammer head. The rest simulation process and the wire icing torsion simulation in the S1 are kept unchanged. The mode is the inherent vibration characteristic of the line conductor, and the relative natural vibration frequency can be intercepted by using the mode analysis in ANSYS software to research the waving suppression effect of the heavy hammer.
S5: determining the influence of a heavy hammer on a torsion angle, setting parameters of a line conductor, and calculating the mass 1070.5kg/km, the elastic modulus 77GPa, the conductor diameter 22.4mm, the span 230m, the height difference 0m and the horizontal tension 31kN; and (6) carrying out simulation. And (4) comparing and analyzing the change of the torsion angle of the wire coated with ice for 10 hours under the four schemes in the S3, and drawing a relation curve of the torsion angle and the position in the gear, as shown in the attached figure 2.
In fig. 2, the maximum torsion angle of the unworn weight is 36.83 °, and the maximum torsion angles of schemes 1 to 4 are 3.5 °, 3.83 °, 4.33 °, and 4.82 °, respectively, so that the effect of the weight on restraining the wire torsion is very obvious. And a concave point appears at the weight suspension, which indicates that the action of the counter-torque provided by the weight effectively clamps the torque of the eccentric ice coating. The weight can provide a strong anti-twisting moment effect for the ice-coated conductor to inhibit the twisting of the conductor in the ice-coating process, so that the ice-coating process of the conductor can continuously occur on one side (windward side). And along with the increase of the thickness of the ice coating, the phenomenon that the ice coating bonding moment can not resist the self gravity moment of the ice coating can occur, the macroscopic expression is that the ice coating falls off layer by layer, and particularly under the action of natural wind, the falling off can be particularly violent, so that the ice coating degree of the wire is reduced, the increase of the sag stress of the wire is reduced, and the safety and the stability of the operation of the wire are further improved.
S6: analyzing the inhibition effect of the heavy hammer on the waving, and based on a Nigol torsion mechanism: for a flexible cable structure such as a single conductor, the degree of separation of the 3 < rd > order transverse vibration frequency and the 1 < st > order torsional vibration frequency may reflect its own galloping inhibition capability. And introducing a resonance margin ζ quantitatively describes the degree of separation between the two frequencies.
ζ＝f t /f v3 (17)
Modal analysis of the iced conductor was performed according to the conductor parameters of fig. 3, and fig. 4 was obtained.
In FIG. 4, the scheme N is a control group without a weight on the wire, and the schemes 1-4 are weight test groups. It can be found that the difference between the frequency of the 1 st order torsional vibration of the scheme with the heavy hammer is larger, and the frequency of the 3 rd order transverse vibration is improved less; the overall resonance margin under the 4 schemes is respectively lifted from 3.0029 to 4.4763, 4.4192, 4.3792 and 4.3652, and is lifted by 49.06%, 47.16%, 45.83% and 45.37%.
The 4 counter weight arrangement schemes can effectively improve the anti-galloping capability of the ice-coated line, and the main reason is that the counter weight improves the overall torsional rigidity of the ice-coated conductor, so that on one hand, the 3-order transverse vibration frequency is indirectly influenced, and the vibration frequency is slightly increased; on the other hand, the reduction of the natural frequency of the torsional vibration caused by ice coating is counteracted, and simultaneously, the 1 st order torsional vibration frequency is greatly improved, so that the separation of 2 frequencies is realized, and the separation is consistent with the theoretical analysis of the mechanism of suppressing the torsional vibration and preventing the galloping of the heavy hammer.
While the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to the above embodiments, and various changes, which relate to the related art known to those skilled in the art and fall within the scope of the present invention, can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Many other changes and modifications can be made without departing from the spirit and scope of the invention. It is to be understood that the invention is not to be limited to the specific embodiments, but only by the scope of the appended claims.
Claims (3)
1. A method for simulating the galloping inhibition value of an ice-coated conductor based on a heavy hammer is characterized by comprising the following steps of:
s1: conducting wire icing torsion statics simulation;
s2: determining structural parameters of a heavy hammer, assuming that the section of an icing line is in a typical crescent shape, evenly icing in a full span, simplifying a lumped mass system by adopting a lumped parameter model, combining the device with the whole line, and finding out the length L of a hammer handle meeting any torsion angle through an optimization equation p And the mass M of the hammer head p The optimal combination parameter of (2);
s3: as shown in step S2, the optimal quality calculated by the optimization model is the total quality of the whole span; according to the multipoint weighting principle, in a span, if a heavy object is arranged at different points in a span, a plurality of nodes can be formed, so that a line system vibrates in a higher order, the vibration amplitude is reduced, and the damage to a transmission line is reduced, therefore, the arrangement mode of a heavy hammer needs to be reasonably selected, and the following 4 schemes are given for simulation in order to research the ice coating torsion and galloping inhibition effects of a lead of the heavy hammer:
in the first scheme, 4 heavy hammers are arranged at equal intervals and equal mass;
in the second scheme, 6 heavy hammers are arranged at equal intervals and equal mass;
according to the third scheme, 8 heavy hammers are arranged at equal intervals and equal mass;
in the fourth scheme, 10 heavy hammers are arranged at equal intervals and equal mass;
s4: adding a heavy hammer model based on the dynamic icing simulation in the step S1;
s5: determining the influence of a heavy hammer on a torsion angle, setting line conductor parameters, comparing and analyzing the change of the torsion angle of the conductor subjected to icing for 10 hours under the four schemes in the step S4, and drawing a relation curve between the torsion angle and the position in a gear;
s6: analyzing the inhibition effect of the heavy hammer on the waving, and based on a Nigol torsion mechanism: for a flexible cable structure such as a single wire, the separation degree of the 3-order transverse vibration frequency and the 1-order torsional vibration frequency can reflect the galloping inhibition capability of the flexible cable structure; and introducing a resonance margin ζ quantitatively describes the degree of separation between the two frequencies.
2. The method for simulating the ice-coated conductor galloping inhibition value based on the heavy hammer as claimed in claim 1, wherein: the static simulation step of the lead comprises the following steps:
(1) Defining related physical parameters of the line, including span, height difference, sag and wire diameter;
(2) Defining the properties of the wire material, including elastic modulus, wire density and Poisson ratio;
(3) The unit property is defined as a Beam188 unit, the Beam188 unit is a three-dimensional Beam unit and is provided with two nodes, and each node of the Beam188 unit has 6 degrees of freedom and can simulate tension, compression and torsion;
the power transmission conductor simulates an ice-coated conductor by using a Beam188 unit;
(4) Establishing key points, establishing a geometric model of the lead, executing grid division, releasing the freedom degrees of torsion and displacement in the lead and applying initial strain;
(5) After the conducting wire steps, opening a large deformation switch, applying gravity, and conducting wire shape finding under the axial force iteration termination condition of the middle unit; and finally, calculating the twisting angle of the lead by applying the torque of the lead through the ice weight and the gravity center obtained by fluid simulation calculation.
3. The method as claimed in claim 2, wherein the weight-based ice-coated conductor galloping suppression numerical simulation method comprises: in step S4, the effect of the weight on the twisting of the conductor comes from the torque and the weight provided by the weight; therefore, for the wire icing torsion simulation of the suspended weight, only the gravity provided by the weight needs to be added when the wire is shaped in the step (5) of the wire icing torsion simulation in the step S1, and the ice load torque and the weight torque are calculated together when the torsion angle is calculated, in the statics simulation, the core parameters of the weight are the length of the hammer handle and the weight of the hammer head, and meanwhile, the weight can be twisted together with the wire, so that the large-rigidity BEAM unit BEAM188 with a given length is adopted to simulate the hammer handle, and the MASS21 unit with MASS effect only in the direction of the hammer head is fixed at one end of the weight to simulate the hammer head; the rest simulation processes and the wire icing torsion simulation in the step S1 are kept unchanged; the mode is the inherent vibration characteristic of the line conductor, and the relative natural vibration frequency is intercepted by using the mode analysis in ANSYS software so as to research the effect of the heavy hammer on inhibiting the galloping.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117688818A (en) * | 2024-01-31 | 2024-03-12 | 合肥工业大学 | Numerical simulation method for power distribution network line galloping and failure rules under extreme weather |
| CN117688818B (en) * | 2024-01-31 | 2024-04-30 | 合肥工业大学 | Numerical simulation method for power distribution network line galloping and failure rules under extreme weather |
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